Defective immunoregulation in multiple sclerosis.

Imbalances in T cell subpopulations have been reported in multiple sclerosis (MS). In the present study of 31 MS patients, the percentage of T cells with Fc receptors for IgG (Tg) was found to be increased in patients with chronic progressive disease, and another T cell subset binding to the Raji B lymphoid cell line was decreased. An inverse correlation (r = -0.675; < 95% confidence limit) was found between these two subsets, suggesting that they vary inversely in MS. The mitogenic responses of MS mononuclear cells, isolated T cells, and recombinet T and non-T cells to the lectins phytohemagglutinin and pokeweek mitogen (PWM) did not differ from those of normal cells. However, more immunoglobulin (Ig)-producing cells were generated in a PWM-driven system with cells from MS patients than with cells from age-matched controls (p < 0.05). Autologous recombination of separated T and non-T cells did not significantly modify these results. T cells from MS patients added to B cells from normal controls exerted an effect that was related to their percentage of Tg cells; that is, values above 15% were associated with a suppression of Ig production, whereas for Tg values below 12%, a helper effect or no modification was observed. These results suggest that changes in T cell subsets in MS are related to changes in functional ability to modulate Ig production by normal B cells. However, MS B cells partly escape regulation by their own T cells, suggesting an associated B cell hyperactivity.